Change in cervical length after therapeutic McDonald cerclage using a transvaginal ultrasonography as a predictor of term delivery

Rhee, Yun Ee

Abstract

OBJECTIVES
To determine the change in cervical length after cerclage and whether a transvaginal ultrasonographic measurement about change in cervical lengthening after cerclage is predictive of term delivery
METHODS
Twenty-nine single pregnant women were suspected as cervical incompetence by using a serial transvaginal ultrasonography. When a shortening of the cervix was substantial before 25 weeks' gestation, a therapeuric McDonald cerclage was applied. The 29 pregnant women had a transvaginal ultrasonographic measurement of the cervix within 48-72 hours before and after cerclage. At each examination, the first measurement was discarded, and the mean of the subsequent three measurements was calculated. Statistical analysis was performed by use of SAS with the significance set at the 5% level.
RESULTS
In the 29 single pregnancies examined, the mean cervical length (distance between internal os and external os) before cerclage was 30.0+/-4.5 mm. A cerclage was applied at the mean gestational age of 16.76+/-3.02 weeks. After the cerclage the mean cervical length increased significantly (r=0.895, p=0.0001) to 34.1+/-4.5 mm. There was a significant relation between the gestational age at delivery and the length of postoperative upper cervix (endocervical canal length above suture) (r=0.378, p=0.043). But there was no significant relation between the gestational age at delivery and the following measurements; preoperative cervical length (r=0.348, p=0.064), postoperative cervical length (r=0.279, p=0.143), cervical lengthening (postoperative cervical length - preoperative cervical length) (r=-0.156, p=0.420), length of postoperative lower cervix (endocervical canal length below suture) (r=-0.003, p=0.999).
CONCLUSION
Therapeutic McDonald cerclage results in a longer cervical length as measured by transvaginal ultrasonography. The increase in cervical length after cerclage is not a predictive term delivery. But the Length in upper cervix after cerclage correlated with gestational weeks at delivery.